Disconnect during Connection Process after Successful Disconnect

RE: Disconnect during Connection Process after Successful Disconnect

run_ar — Fri, 12 May 2017 12:41:57 GMT

Since you say this only fail with certain centrals. And it looks like there is always a timeout. I would guess the central either stops sending packets or is sending them outside of the listening window. I see from the log the central ppm value is set to 31 to 50. If I remember correctly this has been changed to 250 on newer devices (or is it iOS version, not sure). But you say that you have already tried to increase the ppm value on the peripheral so I'm inclined to think the central stopped transmitting for some reason. Did you test the peripheral even with the 500ppm value? You wouldn't happen to have access to an ellisys sniffer so we can get a better trace? maybe see if the master actually stops sending packets (the nRF sniffer is great, but has some limitations...)?

RE: Disconnect during Connection Process after Successful Disconnect

chalecampb — Fri, 05 May 2017 19:26:53 GMT

Hi run_ar,

I have requested XCode logs to see, I asked the app developer and he says there is no disconnect call unless the user manually presses disconnect
The clock source is an external xtal and capacitor pair, we use the same external clock circuit on all of our products in the same layout. The components are 1x FC-135 32.7680KA-AC and 2x GRM1555C1H120GA01D

support.epson.biz/.../doc_check.php

search.murata.co.jp/.../GRM1555C1H120GA01-01.pdf

The capacitor values are 12pF to account for around 2pF in trace capacitance. I just double checked and we are reading mean 32.768kHz, but the minimum and maximum measured frequency are 32720 and 32800. I'll check into why it measures that, since the crystal is rated at 20ppm.

In any case this is the only product and firmware we are seeing the issue on, so I would be surprised to see a hardware issue unless it is exacerbated by something we changed in the software.

Thanks, -Alex

RE: Disconnect during Connection Process after Successful Disconnect

run_ar — Fri, 05 May 2017 13:35:35 GMT

How many peripheral device have you tested that behaves like this (That is how many different chips have you run this particular project on and seen this behavior)? What is your 32KHz clock source?

Could be interesting to see the logs from the apple device as well if you have access to them? They can be retrieved using xcode.

RE: Disconnect during Connection Process after Successful Disconnect

chalecampb — Thu, 27 Apr 2017 14:01:15 GMT

Hi run_ar,

Yes, I asked to check if the problem still occurs with LightBlue and it still disconnected
We did switch from Keil to GCC. This project was the first project we did with the nRF51822. The codebase used Keil because the GCC stationary was not complete at that time. Since then we did 2 other projects, a central and a peripheral. In switching from Keil to GCC, we started from the peripheral makefile that we already had (and shipped). All of the preprocessor directives are the same, the only thing that changed was the include and c file list. And the name.

The issue doesn't occur with the other peripheral project that we use.

RE: Disconnect during Connection Process after Successful Disconnect

run_ar — Thu, 27 Apr 2017 10:34:59 GMT

In the question, are you saying that you switched copmiler from Keil to GCC, and this started after the switch? No changes to the codebase? Are you sure you are not missing any preprocessor symbols?

Have you been able to recreate this behavior using an SDK example so I can try to recreate it here (Unfortunately I don't have a matching idevice/iOS version combination so it might not be possible for me to recreate it...)?

Do you see the same disconnect issue if you use nRF connect for iOS instead of your own app?

RE: Disconnect during Connection Process after Successful Disconnect

chalecampb — Wed, 26 Apr 2017 16:55:45 GMT

@endnode I am not referring to the fact that the device terminates the link as a BT SIG violation. I am referring to a specific set of posts on the forum that details a problem in which the iOS device, after 8.3.2, can potentially send multiple packets which raises a link layer error.

RE: Disconnect during Connection Process after Successful Disconnect

run_ar — Fri, 21 Apr 2017 12:52:33 GMT

As endnode says, it would be interesting to see sniffer traces that shows this problem. Thanks.

RE: Disconnect during Connection Process after Successful Disconnect

endnode — Thu, 20 Apr 2017 22:24:49 GMT

Hi Alex,

Firstly if some device terminates the link it doesn't immediately means it violates BT SIG specification;) Get the RF logs from Nordic Sniffer (or from some more expensive device if available), I guess you will see what is really happening instead of assuming from incomplete iOS and RTT logs.